Capacitor

• US 4,480,285 A
• Filed: 12/15/1982
• Issued: 10/30/1984
• Est. Priority Date: 12/15/1982
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Grahame, Frederick W.
• Primary Examiner(s): GRIFFIN, DONALD
• Application Number:
  US06/449,896
• Time in Patent Office: 685 Days
• Field of Search: 361/273, 361/303-315, 361/323, 361/324
• US Class Current: 361/306.1
• CPC Class Codes: H01G 4/32 Wound capacitors

Abstract

An electrical capacitor is disclosed comprising a doubly metallized electrode and a metal foil electrode interleaved with a dielectric material. In a preferred embodiment the electrodes and dielectric comprise strips formed into a roll wherein, at each end, one edge of an electrode protrudes beyond the edge of the other electrode and defines a planar roll end. A coating of metal is applied at each roll end to form electrical connections with the protruding electrode edges. The edge of the other electrode is protected from stray particles of the coating applied at each end by a barrier comprising a selected recess distance and/or shielding provided by the dielectric strip.

Claims

1. An electrical capacitor comprising:

first and second opposite, substantially planar capacitor ends;

first and second electrodes positioned between the planes of said capacitor ends;

each of said electrodes including at least a single layer of conductive material, said layers being substantially parallel to each other and each being bounded by first and second opposite edges, said first-electrode layer being substantially normal to the plane of said first capacitor end and having its first edge disposed in said first end plane, said first edge of said second-electrode layer being recessed a first predetermined distance from said first end plane;

a layer of dielectric material positioned between said electrode layers and substantially parallel thereto including first and second opposite borders substantially parallel to said first and second end planes respectively;

a fold in said dielectric material including said first border, said fold being positioned substantially within said predetermined recess distance of said first edge of said second-electrode layer from said first end plane; and

first and second electrical connecting means for connecting to said first and second electrodes respectively, at least said first connecting means comprising a conductive coating applied to said first capacitor end to make electrical contact with said first edge of said first-electrode layer;

said predetermined recess distance having a selected magnitude, and said fold being adapted to shield said second electrode from stray particles attributable to the application of said conductive coating to said first capacitor end.

2. A capacitor as recited in claim 1 wherein said fold is positioned substantially between said coating and said first edge of said second-electrode layer spaced about 1/16 inch from said second electrode layer, said fold being from about 1/16 to about 5/16 inch in width.

3. A capacitor as recited in claim 1 wherein said second capacitor end is substantially parallel to said first capacitor end and said second edge of said second-electrode layer lies in the plane of said second capacitor end, the second edge of said first-electrode layer being recessed a second predetermined distance from said second end plane;

said second connecting means comprising a conductive coating applied to said second capacitor end to make electrical contact with said second edge of said second-electrode layer;

said dielectric material further comprising a second fold including said second border, said second fold being positioned substantially within said second predetermined recess distance; and

said folds being adapted to shield said first and second electrode layers from stray particles attributable to the application of said coatings to said second and first end planes respectively.

4. A capacitor as recited in claim 3 wherein said first fold is positioned substantially between said coating on said first capacitor end and said first edge of said second-electrode layer spaced about 1/16 inch from the latter layer and said second fold is positioned substantially between said coating on said second capacitor end and said second edge of said first-electrode layer spaced about 1/16 inch from the latter layer.

5. A capacitor as recited in claim 4 wherein each of said folds is about 1/16 to about 5/16 inch in width.

6. A capacitor as recited in claim 1, 3 or 4 wherein at least one of said electrodes comprises metal foil.

7. A capacitor as recited in claim 1, 3 or 4 wherein both of said electrodes comprise metal foil.

8. A capacitor as recited in claim 1 wherein said second electrode comprises metal foil.

9. A capacitor as recited in claim 1 wherein said second electrode comprises metal foil.

10. A capacitor as recited in claim 1 wherein said predetermined recess distance has a magnitude greater than about 3/8 inch.

11. An electrical capacitor comprising:

first and second elongate strip electrodes alternating with first and seond elongate dielectric strips to form a laminate;

said first elongate strip electrode comprising a non-conductive strip having metal deposited on opposite surfaces thereof;

said second electrode comprising a metal foil strip;

each of said strips having first and second substantially parallel, opposite, longitudinal edges;

said strips being wound in the shape of a roll such that said first longitudinal edge of said first electrode defines a first end of said roll as a plane, and said second longitudinal edge of said second electrode defines a second roll end as a plane opposite said first end plane and substantially parallel thereto, said first longitudinal edge of said second electrode being recessed a predetermined distance from said first end plane, said second longitudinal edge of said first electrode being recessed from said second end plane;

said first strip of dielectric material being interposed between said electrodes and being defined by first and second longitudinal borders recessed from said first and second end planes respectively;

a fold including said first border, said fold being positioned substantially within said predetermined recess distance of said first edge of said second electrode from said first end plane;

a conductive coating applied to a limited area of each of said planar roll ends, each of said coatings establishing an electrical connection with the edge which defines the corresponding roll end, said fold being adapted to shield said second electrode from stray particles attributed to the application of said coating to said first roll end;

said predetermined recess distance being greater than about 3/8 inch; and

connecting leads affixed to said roll, each in electrical contact with one of said coatings.

12. A capacitor as recited in claim 11, wherein:

said dielectric strips comprise synthetic resin;

said nonconductive strip electrode comprises Kraft paper having metal deposited on opposite surfaces thereof; and

said metal foil strip electrode comprises aluminum foil.

13. A capacitor as recited in claim 11 or 12 wherein said predetermined recess distance is in the range of about 1/8 to about 7/16 inch.

14. A capacitor as recited in claim 13 wherein said dielectric strips comprise polypropylene.

15. A capacitor as recited in claim 11 wherein said fold is positioned substantially between said coating and said first edge of said second electrode spaced about 1/16 inch from said second electrode, said fold being from about 1/16 to about 5/16 inch in width.

16. A capacitor as recited in claim 11 wherein said fold is formed by doubling said first border back about 180°

toward said foil electrode.

17. A capacitor as recited in claim 11 wherein said strip of dielectric material interposed between said electrodes further comprises a second fold including said second border, each of said first and second folds being positioned substantially within said recess distance of said strip electrode edges from their corresponding end planes, said folds being adapted to shield said first and second electrodes from stray particles attributable to the application of said coatings to said second and first end planes respectively.

18. A capacitor as recited in claim 17 wherein said first fold is positioned substantially between said coating on said first roll end and said first edge of said second electrode spaced about 1/16 inch from the latter edge, and said second fold is positioned substantially between said coating on said second roll end and said second edge of said first electrode spaced about 1/16 inch from the latter edge.

19. A capacitor as recited in claim 18 wherein each of said folds is about 1/16 to about 5/16 inch in width.

20. An electrical roll capacitor comprising in combination:

an elongate strip electrode comprising Kraft paper having metal deposited on opposite surfaces thereof and including first and second opposite, substantially parallel, longitudinal edges;

an integral elongate self-supporting aluminum foil strip electrode including first and second opposite, substantially parallel, longitudinal edges;

first and second elongate strips of polypropylene dielectric material;

said pair of strip electrodes being interleaved with said dielectric strips to form a roll laminate such that only one each of said dielectric strips lies between said electrodes;

said dielectric strips having first and second longitudinal borders substantially parallel to said edges, said first longitudinal edge of said metallized paper strip extending beyond the other layers of said rolled laminate in an axial direction to define a planar first roll end, and said second longitudinal edge of said aluminum foil electrode extending beyond the other layers of said rolled laminate in an axial direction to define a planar second roll end opposite and substantially parallel to said first roll end, said first longitudinal edge of said foil electrode being recessed about 3/8 to 7/16 inch from the plane of said first roll end, said second longitudinal edge of said doubly metallized electrode being recessed a predetermined recess distance from the plane of said second roll end;

said first longitudinal border of said first dielectric strip being doubled over up to about 180°

toward said aluminum strip electrode to form a fold about 1/16 to 5/16 inch in width, said fold being spaced about 1/16 to 1/8 inch from said first end plane and about 1/16 to 1/4 inch from said first longitudinal edge of said aluminum strip electrode;

a conductive metal coating covering a limited area of each of said roll ends, each of said coatings establishing an electrical connection with the electrode edge which defines the plane of the corresponding roll end; and

a pair of connecting lugs affixed to said roll each in electrical contact with one of said metal coatings.

21. A capacitor as recited in claim 20 wherein said roll is impregnated with a dielectric liquid;

a fluid-tight casing surrounds said roll; and

a pair of terminals on said casing are connected respectively to said lugs.